It has been known that formation of a functional layer on a glass substrate constituting a display screen of a display device imparts a specific function to the display device. For example, Patent Literature 1 discloses a stain-proof touch panel substrate in which an stain-proof film is disposed on a surface of a glass substrate to increase easiness of wiping off fingerprints. Further, Patent Literature 2 discloses a shatterproof film to be attached to a surface of a glass substrate for preventing the glass substrate from shattering upon breakage of the glass substrate.